Virus propagation in animal cell cultures is carried out under temperature conditions that depend on the characteristics of the virus and the host system for propagation. Certain temperatures are selected for the growth of the cells (in cell culture or breeding of embryonic eggs), followed by a selected temperature for the propagation of the virus. In most cases, the virus propagation temperature is lower than the cell propagation temperature. Temperature-sensitive virus propagation relates to influencing the speed of virus propagation and the formation of antigens in a temperature range approximately centered around 20° C. for insect cell cultures (with e.g. Baculovirus production) and at temperatures up to about 37° C. for virus production in mammalian cell culture, with specific optima for each virus/host cell combination. A higher temperature affects both the infection kinetics and viral stability. When viruses are propagated at a temperature of 37° C., a decreased viral titer and lower quality of viral antigen is often observed during the latter periods of viral replication. This effect can have detrimental consequences for large scale virus propagation for vaccine production.
It is a goal of the present invention to provide improved growth conditions which do not affect the quality of the produced antigens for vaccination purposes.